Impedance Tuning and Matching Characteristics of UHF RFID Tag for Increased Reading Range

인식거리 향상을 위한 UHF 대역 RFID 태그 임피던스 정합 설계

  • Lee, Jong-Wook (Department of Radio Communication Engineering, School of Electronics and Information Kyung Hee University) ;
  • Kwon, Hong-Il (Department of Radio Communication Engineering, School of Electronics and Information Kyung Hee University) ;
  • Lee, Bom-Son (Department of Radio Communication Engineering, School of Electronics and Information Kyung Hee University)
  • 이종욱 (경희대학교 전자정보공학부 전파통신) ;
  • 권홍일 (경희대학교 전자정보공학부 전파통신) ;
  • 이범선 (경희대학교 전자정보공학부 전파통신)
  • Published : 2005.11.05

Abstract

We investigated the impedance matching characteristics of UHF-band RFID tag antenna and tag chip for increased reading range. A voltage multiplier designed using 0.4 $\mu$m zero-$V_T$ MOSFET showed that DC output voltage of about 2 V can be obtained using standard CMOS process. The input impedance of the voltage multiplier was examined to achieve impedance matching to the RFID tag antenna using analytical and numerical approaches. The input impedance of the voltage multiplier could be varied in a wide range by selecting the size of MOSFET and the number of multiplying stages, and thus can be impedance matched to a tag antenna in presence of other tag circuit blocks. A meander line inductively-coupled RFID tag antenna operating at UHF band also shows the feasibility of impedance matching to tile RFID tag chip.